Since linguists began extensive work on presupposition in the 1970's, a long and heterogeneous list has been compiled of expressions, expression types and constructions that give rise to presuppositions. In the current literature, the principal (but by no means sole) diagnostic for presupposition typically appealed to is the tendency of the particular element of meaning to project, i.e. to escape the scope of operators such as negation, the question operator, or modals. An important intuition also routinely appealed to is that the element of meaning is in some sense backgrounded, or treated by the speaker as taken for granted. There seems little doubt that there are interesting and theoretically relevant distinctions to be made between different types of presuppositions within this heterogeneous set. But the study of these distinctions is of interest primarily in light of the intuition that the members of this set share some common feature: that there is some singular phenomenon of presupposition to be described and explained. This paper is concerned with what presuppositions have in common, and offers an alternative to the current standard view. On the view currently prevalent in the linguistic literature, presuppositions constitute constraints on the common ground, or on an interlocutor’s “take” on the common ground, at the point at which 1 the presupposing utterance is interpreted. I do not intend to offer here a detailed critique of this standard theory, but perhaps a few words of justification are in order. The motivation for seeking a new account comes in part from the same considerations cited by Abbott 2000, in her critique of the standard view. Abbott’s central point is that the driving idea behind the common ground view is that presuppositions are identified with “old” information, or information that the speaker is treating as “old.” This idea, while perhaps helpful as an initial approximation, rapidly runs up against the observation that it is normal and commonplace for....